As a state-of-the-art design for an integrated CFBL, the CMX improves the . connecting circuitry, details of which are given in the product datasheet. The CMX is an integrated solution for a Cartesian Feedback Loop based linear transmitter. Acting as a direct conversion quadrature mixer from I and Q to RF. CMX datasheet, CMX circuit, CMX data sheet: CMLMICRO – The Product Data Amendment series of documents,alldatasheet, datasheet, Datasheet.

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In the form of a populated PCB, datasueet flexible platform enables users, using a control interface, to configure and evaluate the CMX to various applications and frequency bands. Using a Cartesian transmitter in TDMA systems can be challenging when supporting multiple modulation formats.

The modulation accuracy of a CMX transmit is determined by the down-converter feedback path.

For clarification, the relevant change is: The error amplifier input signal levels will diverge, so the error signal to the up converter will increase, datssheet the signal level to the PA input will also increase.

Note that a different loop-filter might be required for the kHz and kHz channels. Can you help explain how the instability detector on the CMX operates and how it can be used? The results from this improved configuration are also shown in Table 1 and although a small degradation is still observed the carrier leakage is still dBc, which is considered more than datashdet for most applications. The instability detector comprises a high-pass filter followed by a peak-detector circuit and this combination indicates the presence of this high frequency ccmx998.

As phase error increases, the instability detector will show a worsening level of out-band energy.

As this is effectively a stable oscillating condition the instability detector will not detect this operating state. Such dattasheet are unlikely to cause a phase shift as large dmx998 degrees. We can tailor an existing product to your unique requirements Learn more Contact us.


The measurements include the effects of the non-ideal PA that is corrected by the Cartesian loop. A simple guide to help users get started evaluating the DE The data will appear in the grayed-out data box. If the loop is set up degrees out of phase the loop will oscillate and will generally produce a maximum level carrier. EV high resolution schematics and component overlay.

If the loop becomes unstable due to phase inaccuracies the feedback loop will tend to spill energy out-of band. Datasheets CMX Datasheet rev Included are forward and feedback paths; local oscillator circuitry including loop phase control; an instability detector and uncommitted op-amps for input signal conditioning.

CMX – Cartesian Feedback Loop Transmitter – CML Microcircuits

There xmx998 nothing specific to be aware of when powering the EV up for the first time, however it is very important to cmz998 that a 50ohm load is attached to J9 before enabling the power amplifier.

There are three CMX internal registers that are key for this discussion: If a design supports dynamic loop phase calibration then an instability detector event normally triggers loop re-calibration. Typical changes are variations in antenna VSWR and thermal effects.

The error signal produced by the instability detector should be accessed for a particular design and an appropriate threshold set.

CMX998 – Cartesian Feedback Loop Transmitter

The degradation is due to the gain-expansion caused by the linearity correction for the non-ideal PA. This can over-drive the PA which may over-current and fail. I am looking to develop a high quality non-constant envelope transmitter and am looking to improve the linearity of my current cmx99. The wideband noise of the CMX alone at 5MHz offset is typically somewhat better than shown in this plot.


This means a common shift is applied to DC offset correction signal and modulator reference. Are there any particular aspects of power-up datashete down sequence of the EV that I should be aware of?

If you continue to use this site we will assume that you are happy with it. The CMX includes gain adjustment to make threshold setting easier. The instability detector is designed to detect minor phase variations and resultant instability following initial phase correction. The CMX instability detector cannot detect lead or lag error as it works on a simple baseband signal. Do you have any recommended signal-levels that will allow me to see the CMX at its best?

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Both Single Ended and Differential modes are shown. It is important to read the included readme. This process will continue as the PA output ramps down, with the up converter output and PA input signal level continuously increasing.

Cmxx998 recommended way to avoid this is to power-down the CMX down-converter before powering down the PA. Three scripts for evaluating performance of a multi-mode modem using the DE The output power will decrease once the PA is powered down, and this results in a lower signal level fed back into the CMX The PA device is not protected and enabling this device without the load may irreparably dame the device.

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